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Jellyfish rank among the most fascinating and beautiful creatures of the sea. Everyone has heard of a jellyfish, but what exactly are they? The first thing to note is that they are not fish at all, but rather an animal that belongs to the Phylum Cnidaria (cnidos = stinging cells). This phylum also includes the corals, hydras, Portuguese men-of-war, sea anemones, sea pens, sea whips, and sea fans corals. Often referred to as “jellies”, they are made up of 95% water and are found in all oceans and in some freshwater.
Members in the Phylum Cnidaria are most known for their microscopic structures known as nematocysts. These little stinging cells are used for the stunning and capturing of prey. Among all of the jellyfish, only a few present a real danger to people and some species actually lack nematocysts that are capable of penetrating human skin.
The moon jellyfish, Aurelia aurita, is a local of Virginia’s waters and is found throughout all oceans. Found mostly around the coast in warm water, they reach sizes ranging from 2 inches to several feet. Distinguished by their large bell, the moon jellyfish has small threadlike tentacles around the edge that can sting. However, this sting is not powerful enough to pierce though human skin. They feed by trapping microscopic plankton in a film of mucus, which flows over the surface of the bell and is picked off as it reaches the edges by the thick mouth tentacles underneath.
At the museum, the jellyfish are fed daily. They are fed a live brine shrimp called Artemia nauplii. These shrimp are hatched at the museum daily, fed nutrient rich food and then fed fresh to the jellyfish.
So why should we care about jellyfish? Well, they have important roles in the marine environment! Many animals rely on jellyfish as a food source, including sea turtles, over 50 species of fish, marine birds and even other jellies! Juvenile crabs and some species of fish utilize the gelatinous animals as protective havens and a means of distribution.
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